不废话，直接上代码

type Pool struct {
    *gorm.DB
}

func NewPool(db *gorm.DB) *Pool {
    return &Pool{DB: db}
}

func DataToMap[K int64 | string, V int64 | string | float64 | float32](pool *Pool, table Model, NewMap map[K]V, key string, value string, args ...interface{}) error {
    tx := pool.Model(table).Select(key, value)
    if len(args) == 1 {
        tx.Where(args[0])
    } else if len(args) >= 2 {
        tx.Where(args[0], args[1:])
    }
    rows, err := tx.Rows()
    if err != nil {
        return err
    }
    defer rows.Close()
    var k K
    var v V
    for rows.Next() {
        err := rows.Scan(&k, &v)
        if err != nil {
            return err
        }
        NewMap[k] = v
    }
    return nil
}

调用示例

username := make(map[int64]string)
DataToMap(pool, &model.User{}, username, "id", "username")
DataToMap(pool, &model.User{}, username, "id", "username", "`id`<?", 5)

得到结果：

{
    "1": "老男孩",
    "2": "LEO",
    "3": "Lucifer",
    "4": "Tom"
}